Impact hammer element



Dec. 22, 1953 P. E. SCHMID 2,663,395

IMPACT HAMMER ELEMENT Filed Oct. 16, 1951 2 Sheets-Sheet l INVENTOR.

ATTOPA/fy Dec. 22, 1953 P1 E. SCHMID 2,663,395

IMPACT HAMMER ELEMENT Filed Oct. 16, 1951 2 Sheets-Sheet 2 I INVENTOR.

Pau/ f. Job/77m ATTORNEY shape, design Patented Dec. 22, 1953 UNITEDSTATES TENT OFFICE IMPACT HAMIVIEBI; ELEMENT.

Paul E. S'chmid; Houston, Tex assignor to Reed Roller Bit Company;Houston, Tex., a corporation of Texas Application October 16, 1951.,Serial, No. 251,515

clutches and portable, rotary, reversible, pressure fluidactuated tools,such as wrenches, nut runners and thlikegas shown and described in theco-pending patent application- Serial No. 666,707 filed May 2; 1-946,now PateiitNo, 2,580,631, dated January 1, 1952, but more particularlyto the and construction of the hammer elements. used in such tools.

One of the pripcipal' objects of this invention is the provision ofanovel. and simplified hammerelement, of relatively simpledesign, easilymanufactured and operating in thesame eflicientmanner as the morecomplicated and therefore more difiicult to manufacture hammer elementsshown and described in the above entitled application.

Another object of this invention isthe provision in such tools ofimproved means or websengageable by such improved hammer elements forlimiting their movement in at least one direction.

Other objects of this invention will be apparent from the followingdetailed description wherein similar characters of references designatecorresponding parts and wherein:

medium of which the rotor is driven by pressure fluid, preferablycompressed air, admitted thereto in. a conventional manner by means.including a trigger actuated valve, only the trigger [2. of

v which is shownin the drawings.

In addition to the motor already referred to, the tool comprises adriven member having a relatively small moment, of inertia, a flywheelor driving member having a. relatively large, mo.-

ment of inertia, and simple, efiici'ent means for operatively connectingsaid members whereby the driving member. is, caused to successively impact the, driven member.

In the embodimentv shown, the driven member is in the form, of; a. shafti3." rotatably supported in a. bushing l4; fixedly secured in theforward end of a clutch housing i5 detachably connected to the motorhousing l6 by screws, not shown. The reversibility of the driving meansmay be under the control of a sleeve-type reversing valve IT fordirect.- ing the pressure fluid to either peripheral extremity of theconventional, lunate, expansible. chamber surrounding the rotor It. Theforward end of the shaft I3 is provided with a. driving connectionadapted to have an adapter, not

- shown, applied thereto but. which, in turn, is

Figure 1 is a side elevational view, with portions in section,approximately on the line [-4 in Figure 3, of a hand tool embodying thepresent invention;

Figure 2 is a perspectiveview of a portion of 1 the driving member ofthe impact clutch shownin Figure 1.

Figure 3 is a sectional view, approximately on the line 33- of Figure 1,showing a portion of the mechanism in neutral position.

Figures 4, 5, 6, 7 and. 8 are views, similar to; Figure, 3, but showingthev parts, inpositions which they occupy successively during the cycleof. op:- eration.

As previously stated, this. invention is used. in conjunction with theportable tool. shown and described in the co-pending patent applicationSerial No. 666,707, now Patent No; 2,580,631, dated' Jannuary 1, 195.2,which tool constitutes an impact wrench comprising a reversible motordesignated generally by the reference character A, including a rotor It,having radial vanes, or blades H slidably supported within suitablegrooves formed in the rotor and through the adapted to engage a nut,bolt, screw or other similar member which it is desired totishtenremove. The rear'or right-hand end. of the, shaft. l3, as viewedin Fig, 1,, is of slightly greater diameter and is, provided with two,axially spaced, diametrically arranged, arcuately-shaped projee tions oranvils l8, I9 having radial sides 2.0,, 21 adapted to be impinged byradial. surfaces on: plate-like impact 01' hammer members 22, 2,3

- forming a part, of' the built-up flywheel or driving member or hammerassembly, designated generally by the reference character 13.. Theanvils. l6, [9 extend, longitudinally of the shaft it and are impingedby the impact members 22, 23 re,- spectively.

The improved impact members 22, 23 have a. relatively large mass and arep-ivotally connected. by'pins 2d, 25 to an integral cage, designatedgenerally by the reference. character 26. The pins 24',

. 25 are located diametrically opposite each other with respect to theaxis, of rotation oi the. driven member it, which member is coaxiallysupported with respect to the driving or momentum mem-. ber B and therotor Hi. The cage 26 comprises,

three spaced disks 2?, 2:5 and 29 connected by relatively narrow webs32, 3 I, 32, 33 and the rear or right-hand end thereof, as viewed inFigs. 1 and. 2, is keyed to the projecting spindle 34 of the rotor It.The opposite or front end of the cage 26 is rotatably supported on theshaft 13 by a flanged bushing 35 of suitable wear-resisting material.Alternatively the cage may be of built-up construction.

The cage 26, as shown, is counterbored from the front end so as topermit the insertion of the anvil or rear end of the driven member 13.The impact members 22 and 23 are arranged axially with respect to eachother in the cage 25, the impact member 22 being located intermediatethe disk portions 2?, 28 of the cage and the impact member 23 beinglocated intermediate the disk portions 28, 29 of the cage. The pin 24 isfixedly secured in aligned apertures in the disks 2?, 28 ofthe cage. Thedisk 29 is provided with apertures 38 counterbored from the front end ofthe cage to a distance equal to the thickness of the disk 21 to formapertures as continuations of the apertures in the disks 2?, 28 withinone pair of which the pin 22 is located. The radial flange 38 on thebushing 35 which overlies a portion of the aperture within which the pin24 is located prevents axial movement of the pin toward the front of thecage in the event the pin becomes loose in the cage and. the impactmember 23 which overlies the pin 24 prevents its movement in theopposite direction.

The impact members 22, 23 are similar in construction and the pin 25 isassembled in the cage 26 in a manner similar to that in which the pin 24is assembled therein. The shoulder formed by the counterbore in the disk29 within which the pin 25 is located prevents movement of the pintoward the rear in the event it becomes loose in the cage and the impactmember 22 which overlies the pin prevents its movement toward the front.The counterbore in the disk 29 in alignment with the pin 22 merelyfacilitates assembly.

The impact members 22, 23 are narrower than the distance between thewebs 30, 3| and 32, 33, respectively, and the spaces between thedisklike portions 27, 28, and 28, 29 within which the impact members arepositioned are slightly greater than the thickness of the members 22,23, with the result that the members 22, 23 are free to pivot betweenthe webs about the pins 24, 25, respectively.

Referring now more particularly to the invention, the improved impactmembers 22, 23 are alike, each being formed of flat stock resulting intwo parallel end faces located between and in parallel relationship withthe disks 2l28 or 28-29. The one end of each impact member surroundingits pivotal connection with the cage 25 forms a relatively large baseportion 31, while the other end forms a smaller crown portion 33. Thetwo portions are joined by relatively long uninterrupted straight sidewalls 42, 43 converging toward each other from the base 31 and havingtheir edges beveled or chamfered to clear small radii existing betweenthe webs and rings of the cage 25. Each web 30, SI, 32, 33 has arelatively long innermost wall 42 forming a perfectly straightuninterrupted and hat surface of a width substantially equal to thethickness of the impact members 22, 23, the inner walls of the webs 3E,32 being diametrically opposed and parallel to the inner walls of thewebs 3!, 33 respectively. The symmetrical construction of the sides 42,43 with respect to the pivotal axes of the impact members provides forreverse operation of the device, as will be hereinafter apparent.

The center of each impact member is provided with an aperture il definedby arcuateiy-shaped, alternately arranged surfaces 48, 39, 5i connectedby radial or substantially radial surfaces or shoulders 52, 53, 5G, 55.The arcuately-shaped surfaces 48, 29 are of equal radii as are thesurfaces 50, 5| and all have their centers on a line passing through thecenter of the pivot pin 25 and the extreme end of the crown portion 32.The surfaces 52, 5! have a common center and the radii thereof aresmaller than those of the surfaces 48, 49, the centers of Which arespaced apart to provide both the necessary clearance for the anvil l9and to provide ample size for the shoulders 52, 53, 5s and 55. Althoughthe radii of the surfaces 52, iii are smaller than the radii of thesurfaces 43, 49, they are sufficient to permit the anvil associatedtherewith to rotate relative to the impact member when the member isswung to one side or the other about its pivotal connection with thecage 26. The construction of the side walls 22, Q3 and the straightsides as of the webs of the cage 26 with which they engage is such thatthe impact members may move a sufiicient distance to cause the internalradial surfaces 52,23; S l '55 thereof to engage and disengage theexternal Assuming that the flywheel or momentum member B is rotating ina clockwise direction, as indicated by the arrow B, the respective partsare shown in Fig. 8 in a position which they may occupy shortly afterimpact between the shoulder or surface 52 of the impact member 23 withthe surface or shoulder 22 of the anvil i ii. When the shoulder orsurface 52 of the impact member struck or impacted the shoulder 22 ofthe anvil l9, see Fig. '7, the impact member 23 was rotated by thereaction produced, acting in the direction of the force arrow 68, in aclockwise direction about the pin 25 until the side 2-2 struck the side44 of the web 32. This movement of the impact member 23 allowed theshoulder 52 and the surface 5!] to pass around the anvil is. As theshoulders 26, 52 disengage, the flywheel proper accelerates. The centerof mass of the impact member is preferably offset with res ect to theaxis of rotation of the clutch proper and the inertia of the impactmember causes it to tend to lag behind the cage 26.

As soon as the surface 52 passes the rear end of the anvil l2 defined bythe radial surface 2!, which it is about to do, as shown in Fig. 4., theimpact member 23 will be free to rotate in a counterclockwise directionabout the pin 25. At this time the flywheel proper is accelerating anddriving impact member 23 through the pin 25. The effect of inertia ofthe impact member 23, as pre 'viously mentioned, causes the member tolag behind the fiywheel proper whereupon the impact member will movefrom a position with the side wall 2 in engagement with the web 32 shownin Fig. 4 to a position with the side wall 43 in engagement with the web33. The parts then will be in the approximate position shown in Fig. 6and the surface 52 again in position to impinge the surface 20 of theanvil l9.

The: method at cperatiem just described. is: auto-- matic but beingsubject to frictienal. drag ite-- tween the-parts, it" is not positiveand to insure proper setting upcf the impact member for the primaryimpact,. the impact member 23 is providedwiththe internal radial surfaceor shoulder 5 which cooperates with the surface 23 on the anvil;necessary; to: assure proper.- resetting of the impact. memben. As shownin. Fig. 4, the arcuately-shaped surface 5c is about to complete itspassage over the anvil IQ and. the radial surface H t is approachingthe; impact surface 2d of the anvil and in the' event the impact member23 has not been reset by inertia, as explained before, and the side 43not in engagement with the web 33, by the time the shoulder 54 reachesthe shoulder 20, the shoulder 54 will impact or strike the shoulder 26,as indicated in Fig. 5. The anvil is will offer resistance to rotationof the flywheel proper and will act against the shoulder 54 to rotatethe impact member in a counterclockwise direction about the pin untilthe shoulder it strikes the web 33, as indicated in Fig. 6.

The force exerted by the anvil it a ainst the member 23 will act in thedirection indicated by the force arrow 6! and will have a moment arm ofmagnitude 62 about the center of the pin 25.

As themember23rrotaii3ii 2E9 the pin 25, the

shoulders 2!], 54 will be disengaged'a'hd the'arcu- Mewhaped surface. 5|will be permitted to pass about the anvil I 9, see Fig. 6, whereupon thefly- ,wheel continues to rotate freely until impact is made between thesurfaces or shoulders 20, 52,

number of impacts be obtained an eachrotation ofthe flywheel;

The: anvils I83 I? and the impact members 22 2c: are symmetricalwithrespect' to a central plane, from which it follows thatthe clutch oroperative connection between the driving member B and the driven" memberF3 is reversible; therefore, it fSrGHI y necessary-to employ areversible motora-nd the toolis: suitable for tightening or' looseningnuts: bolts, screws and the-- like. Referring to the operation of." theimpactmember-Zfi, when the drive is reversed theshoulders- Z-I 53' andcorrespond with: the shoulders 2c; 52' and- 54, respectively.

The straight side walls 42; 43 of the impact members 22, 23 engageablewith the straight innermost surface 44 of the webs 39, 3|, 32, 33provide relatively large and durable contact areas between the impactmembers and the cake 26, which can readily withstand wear resulting fromimpc ct, and can remain in perfect operative condition during the entirelife of the tool.

I claim:

1. An impact driving connection comprising a rotatably supported drivenmember, a rotatable driving member coaxially supported with respect tosaid driven member, a cylindrical hammer carrier between said membersconnected to said driving member for rotation therewith,

a pair of axially spaced and diametrically opposed anvils on said drivenmember and within said carrier, a hollow hammer element surrounding eachanvil and pivotally connected to said carrier for rotation therewith andpivotal movement shoulder 52 strikes the shoulder? is'somewhat---5-:relative thereto, each hammer element having similar to that existingwhen the shoulder 5-! strikes the shoulder 20 shown in Fig. 5 but themoment arm of the impact force about the center of the pin 25 is muchshorter than the moment arm 6'2, with the result that the impact or blowdelivered to the anvil I9 is considerably greater and. has considerableforce.

It will be noted that the power is transmitted to the impact memberthrough the pivot pin 25 and that the shoulder 52 is adjacent to buttrails the axis about which the impact member is pivoted to the drivingmember or flywheel proper. By varying the radial position of the pivotwith respect to the shoulder 52, etc., or by varying the angularposition of the shoulder 52 with respect to the pivot, the moment arm 62can be increased or decreased to very the blow imparted to the anvil.The same is true of the shoulder 54 which, as shown, leads the pivot forthe impact member. When the shoulder 52 strikes the shoulder 20 of theanvil, the reaction produces a clockwise acceleration of the impactmember 23 about the pin 25 which because of the relatively large mass ofthe impact member, adds to the force of impact, moves the side wall :22into engagement with the straight surface c4 of the web 32, disengagesthe shoulders 2t, 52 and permits the flywheel to resume rotation aboutthe anvil. While the engaging surface 52 and 54 on the impact member 23,and 20 on the anvil l9, respectively, are preferably redial, they may bevaried slightly from a true radial position so as to facilitate theirdisengagement and eliminate all possibility of their hanging together,if desired. The anvils I8, l9 and the pivots for the impact members 22,23 are offset degrees, and two power blows or impacts which act as acouple are effected upon each rotation of the flywheel assembly B.Obviously any number of impact members and anvils may be employed, inwhich event any desired fall an internal shoulder movable into and outof the path of its respective anvil by virtue of said pivotal movementfor delivering a succession of impacts to said anvil, said carrierhaving a pair of relatively long uninterrupted straight innermostparallel surfaces, and at least one relatively long uninterruptedstraight external side wall on said hammer element engageable with oneof said surfaces for limiting the pivotal movement of said hammerelement.

2. An impact driving connection comprising a rotatably supported drivenmember, a rotatable driving member coaxially supported with respect tosaid driven member, a cylindrical hammer carrier between said membersconnected to said driving member for rotation therewith, a pair ofaxially spaced and diametrically opposed anvils on said driven memberand within said carrier, a hollow hammer element surrounding each anviland pivotally connected to said carrier for rotation therewith andpivotal movement relative thereto, each hammer element having aninternal shoulder movable into and out of the path of its respectiveanvil by virtue of said pivotal movement for delivering a succession ofimpacts to said anvil, said carrier having a pair of relatively longuninterrupted straight innermost parallel surfaces, said hammer elementhaving a base and a crown portion joined by relatively longuninterrupted straight external side Walls one engageable with one ofsaid surfaces for limiting the pivotal movement of said hammer element.

3. An impact driving connection comprising a rotatably supported drivenmember, a rotatable driving member coaxially supported with respect tosaid driven member, a cylindrical hammer carrier between said membersconnected to said driving member for rotation therewith, a pair ofaxially spaced and diametrically opposed anvils on said driven memberand within said carrier. a hollow hammer element surrounding each anviland pivotally connected to said carrier for rotation therewith and.pivotal movement relative thereto, each hammer element having aninternal shoulder movable into and out of the path of its respectiveanvil by virtue of said pivotal movement for delivering a succession ofimpacts to said anvil, a plurality of longitudinally extending websforming an integral part of said carrier each having a relatively longuninterrupted straight innermost surface, said hammer element having abase and a crown portion joined by rela- PAUL E. SCHMID.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,425,427 Fitch Aug. 12, 1947 2,580,631 Whitledge Jan. 1, 1952

